선형 보간법을 이용한 시간과 주파수 조합영역에서의 피치 추정 방법

김기출(Kichul Kim),박성주(Sung-Joo Park),이석필(Seok-Pil Lee),김무영(Moo Young Kim) 大韓電子工學會 2010 電子工學會論文誌-SP (Signal processing) Vol.47 No.5

본 논문은 피치를 추출하는 방법으로 자기상관을 이용하였다. 시간과 주파수 영역의 자기상관은 서로 다른 특성을 가지고 있으며, 각각 피치주기와 기본주파수에 대응된다. 본 논문에서는 시간과 주파수 영역에서의 자기상관을 결합하는 방법을 이용하였다. 이 방법은 자기상관에서 발생하는 피치 doubling과 having 에러를 크게 개선시킬 수 있었다. 하지만, 시간과 주파수 영역에서 유성음의 주기적 특성인 피치주기와 기본주파수는 서로 역수 관계이며, 특히 기본주파수의 에러는 FFT의 분해능에 의하여 발생된다. 이러한 영향을 줄이기 위하여 시간 영역과 주파수 영역에서의 자기상관 결합에 보간법을 적용함으로써 피치검출율을 향상 시킬 수 있었다. 자기상관을 결합할 때 시간영역에서 찾은 피치후보들에 대해서만 주파수영역의 자기상관을 구함으로써 계산량은 감축될 수 있었다. 또한, 선형보간을 이용하여 기존방법 보다 FFT 계수를 8배 줄일 수 있었다. 그 결과, FFT 연산량과 주파수영역의 자기상관 계산량을 크게 감축하여 기존 방법 대비 알고리즘 처리시간을 약 9.5배 줄일 수 있었다. An autocorrelation method is used in pitch estimation. Autocorrelation values in time and frequency domains, which have different characteristics, correspond to the pitch period and fundamental frequency, respectively. We utilize an integrated autocorrelation method in time and frequency domains. It can remove the errors of pitch doubling and having. In the time and frequency domains, pitch period and fundamental frequency have reciprocal relation to each other. Especially, fundamental frequency estimation ends up as an error because of the resolution of FFT. To reduce these artifacts, interpolation methods are applied in the integrated autocorrelation domain, which decreases pitch errors. Moreover, only for the pitch candidates found in a time domain, the corresponding frequency-domain autocorrelation values are calculated with reduced computational complexity. Using linear interpolation, we can decrease the required number of FFT coefficients by 8 times. Thus, compared to the conventional methods, computational complexity can be reduced by 9.5 times.

Unsteady Aerodynamic Characteristics depending on Reduced Frequency for a Pitching NACA0012 Airfoil at Re_c=2.3X10^4

김동하,장조원,손명환 한국항공우주학회 2017 International Journal of Aeronautical and Space Sc Vol.18 No.1

Most of small air vehicles with moving wing fly at low Reynolds number condition and the reduced frequency of the moving wing ranges from 0.0 to 1.0. The physical phenomena over the wing dramatically vary with the reduced frequency. This study examines experimentally the effect of the reduced frequency at low Reynolds number. The NACA0012 airfoil performs sinusoidal pitching motion with respect to the quarter chord with the four reduced frequencies of 0.1, 0.2, 0.4 and 0.76 at the Reynolds number 2.3×104. Smoke-wire flow visualization, unsteady surface pressure measurement, and unsteady force calculation are conducted. At the reduced frequency of 0.1 and 0.2, various boundary layer events such as reverse flow, discrete vortices, separation and reattachment change the amplitude and the rotation direction of the unsteady force hysteresis. However, the boundary layer events abruptly disappear at the reduced frequency of 0.4 and 0.76. Especially at the reduced frequency of 0.76, the local variation of the unsteady force with respect to the angle of attack completely vanishes. These results lead us to the conclusion that the unsteady aerodynamic characteristics of the reduced frequency of 0.2 and 0.4 are clearly distinguishable and the unsteady aerodynamic characteristics below the reduced frequency of 0.2 are governed by the boundary layer events.

Unsteady Aerodynamic Characteristics depending on Reduced Frequency for a Pitching NACA0012 Airfoil at Re<SUB>c</SUB>=2.3×10⁴

Dong-Ha Kim,Jo-Won Chang,Myong Hwan Sohn 한국항공우주학회 2017 International Journal of Aeronautical and Space Sc Vol.18 No.1

Most of small air vehicles with moving wing fly at low Reynolds number condition and the reduced frequency of the moving wing ranges from 0.0 to 1.0. The physical phenomena over the wing dramatically vary with the reduced frequency. This study examines experimentally the effect of the reduced frequency at low Reynolds number. The NACA0012 airfoil performs sinusoidal pitching motion with respect to the quarter chord with the four reduced frequencies of 0.1, 0.2, 0.4 and 0.76 at the Reynolds number 2.3×10⁴. Smoke-wire flow visualization, unsteady surface pressure measurement, and unsteady force calculation are conducted. At the reduced frequency of 0.1 and 0.2, various boundary layer events such as reverse flow, discrete vortices, separation and reattachment change the amplitude and the rotation direction of the unsteady force hysteresis. However, the boundary layer events abruptly disappear at the reduced frequency of 0.4 and 0.76. Especially at the reduced frequency of 0.76, the local variation of the unsteady force with respect to the angle of attack completely vanishes. These results lead us to the conclusion that the unsteady aerodynamic characteristics of the reduced frequency of 0.2 and 0.4 are clearly distinguishable and the unsteady aerodynamic characteristics below the reduced frequency of 0.2 are governed by the boundary layer events.

Unsteady Aerodynamic Characteristics depending on Reduced Frequency for a Pitching NACA0012 Airfoil at Re_c=2.3×10⁴

Kim, Dong-Ha,Chang, Jo-Won,Sohn, Myong Hwan The Korean Society for Aeronautical and Space Scie 2017 International Journal of Aeronautical and Space Sc Vol.18 No.1

Most of small air vehicles with moving wing fly at low Reynolds number condition and the reduced frequency of the moving wing ranges from 0.0 to 1.0. The physical phenomena over the wing dramatically vary with the reduced frequency. This study examines experimentally the effect of the reduced frequency at low Reynolds number. The NACA0012 airfoil performs sinusoidal pitching motion with respect to the quarter chord with the four reduced frequencies of 0.1, 0.2, 0.4 and 0.76 at the Reynolds number $2.3{\times}10^4$. Smoke-wire flow visualization, unsteady surface pressure measurement, and unsteady force calculation are conducted. At the reduced frequency of 0.1 and 0.2, various boundary layer events such as reverse flow, discrete vortices, separation and reattachment change the amplitude and the rotation direction of the unsteady force hysteresis. However, the boundary layer events abruptly disappear at the reduced frequency of 0.4 and 0.76. Especially at the reduced frequency of 0.76, the local variation of the unsteady force with respect to the angle of attack completely vanishes. These results lead us to the conclusion that the unsteady aerodynamic characteristics of the reduced frequency of 0.2 and 0.4 are clearly distinguishable and the unsteady aerodynamic characteristics below the reduced frequency of 0.2 are governed by the boundary layer events.

다축 로드 시뮬레이터를 이용한 대형트럭 주요 시스템의 바운스와 롤 및 피치 주파수의 실험적 분석

문일동(Il Dong Moon),오재윤(Chae Youn Oh) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.8

This paper presents a scheme for experimentally analyzing bounce, roll and pitch frequencies of major systems of a large truck using a multi-axial road simulator. The excitation input (amplitude and frequency range) for a frequency response test with the multi-axial road simulator is selected in order that bounce, roll and pitch modes are not coupled each other, the excitation amplitude can be reproduced in a specified excitation frequency range, and tires do not lose contact with posters. Three accelerometers, one gyroscope and four displacement meters are used in the frequency response test using the multi-axial road simulator. The reliability of the presented bounce mode frequency response test scheme is validated by comparing the result from a test using the multi-axial road simulator with the result from a road driving test. The road driving test is performed with velocities of 20㎞/h and 30㎞/h, and in an unladen state. The vertical accelerations at the cab and the front axle are measured in the road driving test. The roll and pitch mode frequency response tests are also performed with the presented frequency response test scheme. Roll and pitch frequencies of major systems of a large truck that are hard to acquire from a road driving test are analyzed as well as bounce frequency.

Learning Syllable-timed Prosody as a Native Speaker of Stress-timed Prosody

( Jong-mi-kim ) 대한언어학회 2019 언어학 Vol.27 No.2

To see how syllable-timed prosody is learned by a native speaker of a language that uses stress-timed prosody, duration and pitch in the L2 Korean speech of L1 English learners are explored. For analysis, 28 learners were divided into low- and high-proficiency groups, based on native Korean-speaking listeners’ evaluation of the learners’ read Korean speech data. In addition, 12 native speakers of Korean recorded their own Korean speech as a control group and as model speakers. The pairwise variability of 28 adjacent vowels within each accentual phrase was measured in terms of duration and fundamental frequency. The results showed that learners used both pitch (fundamental frequency) variability and duration variability for prominence acquisition, whereas the native speaker controls used only pitch variability. These results suggest the presence of prosodic transfer of contrastive duration for prosodic acquisition of contrastive pitch in adult language learning of syllable-timed prosody.

선천성 청각장애성인의 시각적피드백 이용 음도치료 효과

어수지,윤미선,Euh, Su-Ji,Yoon, Mi-Sun 한국음성학회 2005 음성과학 Vol.12 No.4

This study is an attempt to investigate effect of pitch treatment program using visual feedback for profound deaf adults. Dr. Speech program was applied as a training tool. The subjects of this study were 3 profound deaf adults. Speech samples for evaluation were vowel prolongations and connected speech. Analysis was performed under the principle of single subject research design. As results of this study, all subjects showed the treatment effects which were represented by lowering fundamental frequency and speaking fundamental frequency.

Voice Similarities between Brothers

Ko, Do-Heung,Kang, SunMee 한국음성과학회 2002 음성과학 Vol.9 No.2

This paper aims to provide a guideline for modelling speaker indentification and speaker verification by comparing voice similarities between brothers. Five pairs ofbrothers who are believed to have similar voices participated in this experiment. Before conducted in the experiment, perceptual tests were measured if the voices were similar between brothers. Tfhe words were measured in both isolation and context, and the subjects were asked to read five times with about three seconds of interval between readings. Recordings were made at natural speed in a quiet room. The data were analyzed in pitch and formant frequencies using CSL (Computerized Speech Lab), PCQuirer and MDVP(multi-dimensional Voice Program). It was found that data of the inital vowels are much more similar and homogeneous than those of vowels in other position. Tfhe acoustic data showed that voice similarities are strikingly high in both pitch and formant frequencies. It was also found that the correlation coefficient was not significant betgween parameters above.

직 · 간접흡연 환경에서의 성대 및 음형대 변화에 대한 음성 분석학적 연구

김봉현(Bong-hyun Kim),조동욱(Dong-uk Cho) 한국통신학회 2011 韓國通信學會論文誌 Vol.24 No.7

웰빙이 새로운 미래 사회적 이슈로 부각되면서 건강관리 및 유지에 대한 현대인들의 관심이 증대되고 있다. 특히, 흡연에 대한 좋지 않은 인식이 높아지면서 대대적인 금연 운동이 확산되고 있는 실정이다. 흡연은 인체의 호흡기와 순환기 등에 많은 악영향을 미치며 직접적인 흡연뿐만 아니라 간접흡연도 동일한 증상이 유발되는 치명적인 행위로 인식되고 있다. 따라서 본 논문에서는 직접흡연과 간접흡연 환경에서 성대 및 음형대에 미치는 영향을 음성 분석학적 요소 기술의 적용을 통해 비교, 분석하는 연구를 수행하였다. 이를 위해 20대 남성을 대상으로 흡연자와 비흡연자로 피실험자 집단을 구성하고 직?간접흡연 전과 후의 음성을 수집하여 Pitch, Jitter, Shimmer 및 5~8 Formant Frequency를 적용한 실험 결과를 추출, 분석하는 연구를 수행하였다. Modern people has been increased interest about health care and maintenance as emerging well-being and social issues. In particular, the smoking is not good for the recognition much greater importance is the massive spread of the smoking is low. The smoking has much adverse effects body's respiratory and circulatory organ many and it is recognized as a serious danger to our health the smoking as well as secondhand smoking. In this paper, we were carried out study analysis comparison to apply though voice analytical elements techniques have a influence vocal cords and formants in the environment smoking and secondhand smoking. For this purpose, we organized subjects group smoker and nonsmoker in 20's man and to collect voice of the smoke and Secondhand Smoking before after then we carried out study analysis experimental results Pitch, Jitter, Shimmer, 5~8 Formant Frequency.

Identification of bridge bending frequencies through drive-by monitoring compensating vehicle pitch detrimental effect

Lorenzo Benedetti,Lorenzo Bernardini,Antonio Argentino,Gabriele Cazzulani,Claudio Somaschini,Marco Belloli Techno-Press 2022 Structural monitoring and maintenance Vol.9 No.4

Bridge structural health monitoring with the aim of continuously assessing structural safety and reliability represents a topic of major importance for worldwide infrastructure managers. In the last two decades, due to their potential economic and operational advantages, drive-by approaches experienced growing consideration from researcher and engineers. This work addresses two technical topics regarding indirect frequency estimation methods: bridge and vehicle dynamics overlapping, and bridge expansion joints impact. The experimental campaign was conducted on a mixed multi-span bridge located in Lombardy using a Ford Galaxy instrumented with a mesh of wireless accelerometers. The onboard time series were acquired for a number of 10 passages over the bridge,performed at a travelling speed of 30 km/h, with no limitations imposed to traffic. Exploiting an ad-hoc sensors positioning, pitch vehicle motion was compensated, allowing to estimate the first two bridge bending frequencies from PSD functions; moreover, the herein adopted approach proved to be insensitive to joints disturbance. Conclusively, a sensitivity study has been conducted to trace the relationship between estimation accuracy and number of trips considered in the analysis. Promising results were found, pointing out a clear positive correlation especially for the first bending frequency.